Method for cooling workpieces



April 28, 1970 o. MODDER 3,508,979

METHOD FOR COOLING WORKPIECES Filed March 9, 1966 HHV@ -. :ffffMl-|; 1H

IN\{ ENTOR OTTO MODDER HIS ATTORNEY United States Patent C US. Cl.148-12.4 2 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus forthe rapid cooling of rolled materials from rolling temperature to roomtemperature and, more particularly, to materials such as sheets, billetsor the like that are sensitive to stresses and distortion.

It is known in the art that hot rolled material, when leaving the lastrolling mill stand, can be cooled on hot beds to a desired finaltemperature, e.g. room temperature. After the individual lengths ofrolled stock arrive on the hot bed they are moved forward essentiallyperpendicular to their longitudinal axes at a low conveying speed suchthat successive lengths of rolled stock come to rest on the hot bed nextto one another with practically zero clearance between them.

The cooling from rolling temperature which may be as high as 1100 C.down to about 650 C. occurs relatively rapidly because the temperaturedifference is relatively great between rolling temperature and roomtemperature. On the other hand, the cooling of the rolled material from650 C. down to room temperature requires a considerably longer period oftime as the removal of heat proceeds substantially slower, due to thesmaller temperature dilference between the cooling stock and thesurrounding medium provoking the heat evacuation, which in this case, itis the ambient air. Under these conditions the hot beds, especially withthe present-day rolling speed, must be very large and designed underconsiderable expenditure and substantial space requirement.

For the rapid cooling of heavy rolled material, e.g. blooms or slabs, itis also known in the art to dip the material into water or a similarliquid coolant and move it therein to a certain extent in order to avoidthe formation of steam bubbles. The liquid coolant brings aboutessentially better heat evacuation and, therefore, accelerated coolingof the rolled material, especially when the coolant is subject tocontinuous agitation. Direct cooling of rolled material with relativelysmall sections, such as billets, sheets, bars, sections or the like, inwater or a similar coolant was heretofore unfeasible, because suchrolled material became warped and twisted as the result of frequentlyoccurring thermal stresses. Further processing of this material,therefore, would be impossible in many cases. To this day, therefore,small-section rolled material has been cooled from the rollingtemperature down to the desired end temperature while making use of theconventional hot beds that are large in their layout and, therefore,procurable only at considerable expenditures.

It is the object of the present invention to eliminate theaforementioned drawbacks of the known art. Therefore, the invention isbased on a method and apparatus for the rapid cooling of hot rolledstock, such as sheets, billets or the like, from the rolling temperaturewithin the range of approximately 780 to 1100 C. down to roomtemperature and by employing said method and/or apparatus the timeconsumed and the constructional expenditure can be reduced to a fractionof what it used to be, without difiiculties relative to warping, bendingor twisting of the rolled material. From the point of view of processingengineering the solution of this problem resides essentially in the factthat the cooling from the rolling temperature down to a temperature ofabout 650 C. occurs under free-air admission, whereupon the rolledproduct for further reduction in temperature is dipped into Water or asimilar coolant.

It turned out that the danger of distortion, bending or twisting of therolled material at a temperature below 650 C. is relatively slight, if,even though, through its immersion in a liquid coolant, e.g. water, acertain quenching sets in.

From the point of view of processing engineering it is furtheradvantageous according to the invention if the rolled material duringthe entire cooling process is kept steadily under continuous ordiscontinuous motion.

A cooling apparatus to carry out the method according to the presentinvention is characterized by a hot bed of known design, eg a skid,roller, rake and lifting-beam hot bed or the like, and immediatelyadjacent thereto an immersion-cooling device, e.g. a cooling wheel or acooling-swinging device.

With such a cooling system it is possible according to this invention todesign the hot bed with a considerably reduced length, e.g. to one-thirdof the customary length, thereby cutting down substantially theexpenditure for the entire cooling apparatus because theimmersion-cooling. device requires relatively little installation spaceand it is otherwise less costly than a conventional hot bed.

In order to assure at any time trouble-free transfer of the rolled stockfrom the hot bed to the immersioncooliug device, it is advisable,depending on the design of the hot bed, to provide between the hot bedand the immersion-cooling device special transfer devices. Especiallywith cooling systems for bar stock, such as billets or sections, it isadvisable to develop the transfer device in such a manner that agroupwise transfer of the rolled material to the immersion-coolingdevice is made possible.

These features and advantages of the present invention will be betterunderstood when the following specification is read along with theaccompanying drawing which schematically illustrates an elevational viewof one embodiment thereof.

The lengths of hot rolled material 1 are delivered from a rolling mill,not shown, on an approach roller table 2 by which they are transferredto the entry end of a hot bed 3 and there lifted individually off theapproach roller table 2 and delivered to the hot bed 3. The hot bed 3may be of any desired construction, i.e. skid, roller, lifting-bea.m, orswinging-rake hot beds or the like may be employed. Represented in thedrawing is a lifting-beam hot bed 3. In this case the transfer of therolled stock lengths 1 from the approach roller table 2 to the hot bed 3as well as the stepwise further transportation of the rolled stocklengths on the hot bed 3 occurs by means of lifting beams 4. The liftingbeams 4 are alternatively raised and lowered by lifting drives 5 and aswing drive 6 is employed to move the beams during the raising in thedirection of the arrow a and during lowering in the direction of thearrow b. As a result thereof, the rolled stock lengths 1 lying closelynext to each other on the hot bed travel slowly toward the delivery endof the hot bed 3. The length of the hot bed 3 is then so dimensionedthat the rolled stock lengths 1, while traveling over the hot bed 3, areexclusively cooled under free-air admission from the rolling temperaturedown to a temperature of about 650 C.

Adjacent to the delivery end of the hot bed 3 is an immersion-coolingapparatus 7 developed as a cooling wheel 9 dipping into a tank filledwith liquid 8. The

lengths of rolled material 1 are transmitted purposely in groups fromthe hot bed 3 to the cooling wheel 9, by a delivery device of knowndesign which shoves a given number of rolled stock lengths 1 intospokelike openings 11 formed in the cooling wheel 9. After each spokeopening 11 is loaded, the cooling wheel 9 is turned by a sector anamount corresponding to the division of the spoke openings 11, so that anext opening 11 comes to lie in an extension of the hot bed 3, whereasthe preceding spoke opening with the rolled stock lengths 1 containedtherein dips into the tank filled with liquid 8. In this liquid tank therolled stock lengths 1 are cooled rapidly from the temperature amountingto about 650 C. down to the desired end temperature or room temperature.The cooled lengths of rolled material 1, on the periphery of the coolingwheel 9 at a point somewhat diametrically opposite to the hot bed 3, aremoved also in a group by an ejecting device 12 coupled to the deliverydevice 10 out of the spoke clearance 11 and, for example, shoveddirectly onto a runout roller table 13.

Because the lengths of rolled material 1 cool in a relatively short timefrom the rolling temperature toa temperature of about 650 C., the hotbed may have a limited length. Since the rolled stock having atemperature of 650 C. can be exposed without the danger of distorting,twisting and bending to quench cooling by dipping into a liquid coolant,there results according to the invention a low-cost and space-savingcooling apparatus for rolled stock with small sections, such as billets,bars, sections and sheets.

It goes without saying that the immersion-cooling device 7, in lieu of acooling wheel 9, can also be developed as a swing-cooling apparatus,which through a swinging motion dips the rolled material into a tankfilled with liquid and removes it therefrom after cooling.

By employing the present invention, the hot bed can be reduced to afraction of the longitudinal dimension of the past and because inaddition thereto the expenditure for the immersion-cooling apparatus issubstantiall lower than for a conventional hot bed, there results asidefrom the substantial shortening of the cooling apparatus, also aconsiderable reduction in the construction costs.

In accordance with the provisions of the patent statutes, I haveexplained the principle and operation of my invention and haveillustrated and described what I consider to represent the bestembodiment thereof. However, I desire to have it understood that withinthe scope of the appended claims, the invention may be practicedotherwise than as specifically illustrated and described.

I claim:

1. A method of rapidly cooling hot rolled material such as sheets,billets, bars and sections immediately following the rolling thereof,which material is sensitive to distortion and twisting caused by thedevelopment of stresses incident to cooling thereof from the rollingtemperature down to room temperature comprising the steps of:

cooling said material immediately following the rolling thereof byfree-air admission from its rolling temperature down to a temperature ofabout 650 C. and immediately thereafter,

further cooling said material by dipping it into water or similarcoolant to further reduce the temperature of said material.

2. A method of rapidly cooling rolled material according to claim 1,including the additional step of imparting motion to said materialduring the cooling of said material by said free-air admission andduring said further cooling of said material by dipping it into water orsimilar coolant.

References Cited UNITED STATES PATENTS RICHARD O. DEAN, Primary ExaminerUS. Cl. X.R. 148-143

